<?php
class water{


    /**
     * 图片加水印（适用于png/jpg/gif格式）
     * 
     * @author 23585472@qq.com
     *
     * @param $srcImg 原图片
     * @param $waterImg 水印图片
     * @param $savepath 保存路径
     * @param $savename 保存名字 
     * @param $positon 水印位置 1左上2左下3居中4右上5右下
     * @param $alpha 透明度 -- 0:完全透明, 100:完全不透明
     * @return 成功 -- 加水印后的新图片地址
     *          失败 -- -1:原文件不存在, -2:水印图片不存在, -3:原文件图像对象建立失败
     *          -4:水印文件图像对象建立失败 -5:加水印后的新图片保存失败
     *使用:
     *    import('ORG.Util.ThumbHandler');
     *    $obj=new water($src);
     *    $src =  APP_PATH .'Uploads/image/20140114/20140114030124_59490.jpg';
     *    $sy  =  APP_PATH .'Uploads/image/20140410/53460cf31f04a.gif';
     *    $savepath = APP_PATH .'Uploads/image/20140114';
     *    $savename = time() . 'xin.jpg';
     *    $obj->img_water_mark($src, $sy, $savepath, $savename, 1, 50);
     */
    function img_water_mark($srcImg, $waterImg, $savepath=null, $savename=null, $positon=5, $alpha=30)
    {
        $temp = pathinfo($srcImg);
        $name = $temp['basename'];
        $path = $temp['dirname'];
        $exte = $temp['extension'];
        $savename = $savename ? $savename : $name;
        $savepath = $savepath ? $savepath : $path;
        $savefile = $savepath .'/'. $savename;


        $srcinfo = @getimagesize($srcImg);
        if (!$srcinfo) {
            return -1; //原文件不存在
        }
        $waterinfo = @getimagesize($waterImg);
        if (!$waterinfo) {
            return -2; //水印图片不存在
        }
        $srcImgObj = $this->image_create_from_ext($srcImg);
        if (!$srcImgObj) {
            return -3; //原文件图像对象建立失败
        }
        $waterImgObj = $this->image_create_from_ext($waterImg);
        if (!$waterImgObj) {
            return -4; //水印文件图像对象建立失败
        }
        switch ($positon) {
        //1顶部居左 
        case 1: $x=$y=0; break;
        //4顶部居右
        case 4: $x = $srcinfo[0]-$waterinfo[0]; $y = 0; break;
        //3居中
        case 3: $x = ($srcinfo[0]-$waterinfo[0])/2; $y = ($srcinfo[1]-$waterinfo[1])/2; break;
        //2底部居左
        case 2: $x = 0; $y = $srcinfo[1]-$waterinfo[1]; break;
        //5底部居右
        case 5: $x = $srcinfo[0]-$waterinfo[0]; $y = $srcinfo[1]-$waterinfo[1]; break;
        default: $x=$y=0;
        }
        imagecopymerge($srcImgObj, $waterImgObj, $x, $y, 0, 0, $waterinfo[0], $waterinfo[1], $alpha);
        switch ($srcinfo[2]) {
            case 1: imagegif($srcImgObj, $savefile); break;
            case 2: imagejpeg($srcImgObj, $savefile); break;
            case 3: imagepng($srcImgObj, $savefile); break;
            default: return -5; //保存失败
        }
        imagedestroy($srcImgObj);
        imagedestroy($waterImgObj);
        return $savefile;
    }


    function image_create_from_ext($imgfile)
    {
        $info = getimagesize($imgfile);
        $im = null;
        switch ($info[2]) {
        case 1: $im=imagecreatefromgif($imgfile); break;
        case 2: $im=imagecreatefromjpeg($imgfile); break;
        case 3: $im=imagecreatefrompng($imgfile); break;
        }
        return $im;
    }

}